The purpose of this proposed project is to increase the caloric intake of young children (18-48 months) with "non organic" failure to thrive and increase positive parent-child interactions during meal times by increasing the reinforcement provided during the meals. This will be accomplished by first using functional analysis procedures to identify positive reinforcers for child compliance during demand situations outside of meal times. These reinforcers will then be inserted into meal times as choices based on matching theory. Single case experimental designs will be used to identify the reinforcers and to evaluate the effects of treatment on parent-child interactions and food acceptance during meal times. Additional measures of caloric intake and growth will be obtained from medical staff and hospital records. Eight children and their families will participate. For each child, the evaluation will occur during a standard inpatient hospitalization for failure to thrive. The durability of the treatment effects will be evaluated during routine outpatient follow-up visits.